The present invention relates, in general, to quality control inspection of, preferably cylindrical, multi-component articles, and more particularly to systems and methods for the inspection of cigarette filter assemblies which systems and methods can be operated and carried out in a high speed manner.
Quality control is important in all phases of manufacturing for many reasons, including product quality, customer satisfaction, production cost management, and speed of manufacture. While the following background description and subsequent description of the invention focus on preferred applications directed to cigarette filter assembly inspection, the present invention is applicable to various processing and production environments in which multi-segment products are produced and unwanted voids or improper segment dimensions can occur within an outer enclosure of the product which prevents ordinary visual inspection without destruction of the product, and where high speed operation is important.
Cigarette manufacturing is generally a high speed process where thousands of individual cigarettes can be made from shredded tobacco, rolls of cigarette paper, and, optionally, filters, in a given minute of operation. In many standard production processes, tobacco enters a machine and is wrapped with cigarette paper to form a continuous rod, and the rod is then cut into single or double-length cigarettes, appended with filters, and ultimately output for packaging. Such processes provide various opportunities for defect formation. For example, the density of the tobacco rod forming a particular cigarette can be an issue. If the rod is determined to be too heavy, for example, then too much tobacco is being used, which can be wasteful. Similarly, for example, a misplaced splice in the cigarette wrapping paper, loose tobacco at an end of a cigarette rod, and improperly attached or missing filters can result.
Another significant problem in high speed production processes relates to the manufacture of multi-segment assemblies, such as, for example, some cigarette filters. For example, some filter assemblies are manufactured to include two or more filter materials such as cellulose acetate separated by another granular material such as activated charcoal. The several segments are provided within a paper wrapping resulting in a multi-segment filter tip which can be attached to a tobacco rod to produce a cigarette. Often, such filters are prepared as extended rod assemblies with several multi-segment groups joined together in one continuous paper rod which is ultimately cut at predetermined positions to provide two or more individual filter tips.
During the high speed production of such rod-shaped products, filling of materials can be less than ideal and unwanted voids or imperfect filling (low density) in a given segment can occur resulting in filters that bend, twist or compact during subsequent processing and produce cigarettes that must be discarded. Additionally, over filling or misalignment of an end-segment can occur resulting in a filter segment material protruding from the wrapping paper.
Thus, during high speed manufacture of cigarettes and like products, quality control parameters are often monitored and reactive measures can be taken to modify the production process or reject the out-of-specification products. Final products can be given an exterior optical inspection, for example using a video camera. The image can be analyzed for the presence of defects. Density inspections have also been suggested in which a cigarette or rod is exposed to some form of electromagnetic radiation to determine density via transmittance of the radiation. Such known inspection systems are not typically concerned with relative placement of internal components of the cigarette, because a tobacco rod and filter typically abut. Moreover, such inspection systems generally evaluate a finished product and do not reject a filter assembly prior to its attachment to a tobacco rod. Accordingly, while an adjustment can later be made to a production line, the tobacco has already been wasted.
Multi-segment cigarette filters can require additional inspections The relative positioning of the interior components of such filter assemblies can be crucial to their proper operation and should be carefully monitored. Visual inspection of a final product to determine the relative placement of components is generally not possible without disassembling the finished cigarette due to the various layers paper or other material surrounding the components. Such disassembly would likely disturb the interior spacing and would, in any event, occur too late in the manufacturing process to provide useful feedback for correcting machine settings in a timely manner. Moreover, known inspection systems which optically measure one or more dimensions of a finished product, do not inform the manufacturer of the presence of voids or loose packing. Visual evaluation of dimensions is limited to exterior wrapping paper and does not provide reliable product quality information.
Accordingly, there is a need in the art for inspection systems and methods that provide reliable quality information for multi-segment products which can contain unwanted voids, loose packings or misaligned segment, and which can provide the information in high speed operations.